docs: update discovery probability to ~22-42% — SEED-007/008, Wave 2 D-amino plan, cross-term scoring (#43) (#43)

* docs: fix stale amphipathicity weight in test_scoring_activity.py docstring (0.15 → 0.14, add helix_bonus)

* docs: update discovery probability to ~22-42% incorporating PRs #39-42 (SEED-007/008, Wave 2 guidance, cross-term scoring)

* fix: correct bombolitin species (B. pennsylvanicus), fix MIC citation attribution, clarify per-candidate vs combined probability methodology

Author: cschanhniem